Fuel cell based power generator

ABSTRACT

A controller for a fuel cell based power generator includes a memory and a processor configured to execute executable instructions stored in the memory to receive a pressure in an anode loop of the fuel cell based power generator, wherein the anode loop includes a hydrogen generator and an anode loop blower, and control the anode loop blower such that the hydrogen generator provides hydrogen to an anode of a fuel cell via the blower and the anode loop at a controlled pressure. In further embodiments, the temperatures of the fuel cell and hydrogen generator are independently controlled.

RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 16/354,077, filed on Mar. 14, 2019. The contents ofthe foregoing are hereby incorporated by reference in their entirety.

BACKGROUND

The run time of unmanned air systems (UAS), sometimes referred to asdrones, is limited by their power sources. State of the art UAS uselight-weight lithium ion/polymer batteries with specific energies thatrange from ˜200-300 Wh/kg, enabling flight times on the order of 20-60min. For emerging applications including infrastructure inspection (e.g.roads, bridges, power lines, rail, pipelines, etc.) and packagedelivery, it may be desired to have greater flight times on a batterycharge, among other suitable applications. In some instances, greaterthan six-hour flight times are desired in order for such UAS to becommercially viable.

Existing obstacles include efficient energy storage and utilizationfaces. Proton exchange membrane (PEM) fuel cells for man-portable powerand micro air vehicles require light-weight, small-size, and high-ratehydrogen sources. Commercially available hydrogen sources such as metalhydrides, compressed hydrogen in cylinders, or catalyticwaterborohydride hydrogen generators are capable of high rate hydrogengeneration, but can be heavy and bulky.

While some hydrogen generators are light-weight and have small size,they are incapable of generating hydrogen at a sufficiently high ratefor many applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a power generator having a fuel celland hydrogen generator according to embodiments of the presentdisclosure.

FIG. 2 is a perspective view of an unmanned air system (UAS)illustrating an open compartment according to embodiments of the presentdisclosure.

FIG. 3 is a method for fuel cell based power generation according toembodiments of the present disclosure.

FIG. 4 is a schematic block diagram of an example controller for fuelcell based power generation according to embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Devices and methods for a fuel cell based power generator are disclosed.In some examples, one or more embodiments include a memory, and aprocessor to execute executable instructions stored in the memory toreceive a pressure in an anode loop of the fuel cell based powergenerator, where the anode loop includes a hydrogen generator and ablower such that the hydrogen generator provides hydrogen to an anode ofa fuel cell via the blower and the anode loop, determine whether thepressure in the anode loop exceeds a threshold pressure, and modify aspeed of the blower to modify the pressure in the anode loop in responseto the determination.

A method includes passing ambient air, via an ambient air path, past acathode side of the fuel cell to a water exchanger, picking up waterfrom the cathode side of the fuel cell and exhausting air and nitrogento ambient, passing hydrogen, via a recirculating primary hydrogen path,where the water exchanger transfers water from the ambient air pathcomprising a cathode stream to the recirculating hydrogen pathcomprising an anode stream, and passing the water to a hydrogengenerator to add hydrogen to the recirculating hydrogen path and passingthe hydrogen via a secondary hydrogen path past the anode side of thefuel cell.

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration specific embodiments which may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that structural, logical, and/orelectrical changes may be made without departing from the scope of thepresent invention. The following description of example embodiments is,therefore, not to be taken in a limited sense, and the scope of thepresent invention is defined by the appended claims.

The functions or algorithms described herein may be implemented insoftware in some embodiments. The software may consist of computerexecutable instructions stored on computer readable media or computerreadable storage device such as one or more non-transitory memories orother type of hardware based storage devices, either local or networked.

Further, such functions correspond to modules, which may be software,hardware, firmware or any combination thereof. Multiple functions may beperformed in one or more modules as desired, and the embodimentsdescribed are merely examples. The software may be executed on a digitalsignal processor, ASIC, microprocessor, or other type of processoroperating on a computer system, such as a personal computer, server orother computer system, turning such computer system into a specificallyprogrammed machine.

In various embodiments of the present disclosure, a high specific energypower source including a fuel cell may be used for battery/fuel cellpowered devices, such as a UAS. Embodiments of the present disclosurecan be capable of, for instance, providing four to twelve times the runtime of state of the art lithium batteries. Some embodiments may, forexample, provide six to twelve or more hours of flight time.

A fuel cell based power generator provides run time improvement andenergy efficiency under specified load power profiles. Moreover, thefuel cell based power generator may be substantially lighter than priorenergy storage devices and may have lower projected lifecycle costs,without compromising operation temperature range or environmental andsafety performance. An improvement in runtime lies in the innovativefuel-cell technology and its fuel chemistry based on lithium aluminumhydride (LAH) that requires no net water consumption in order to sustainits operation, thus eliminating the need for a water fuel reservoir,which enables the energy source to be substantially smaller and lighterthan other conventional chemical hydride or direct methanol fuel cellswith on-board storage of water (fuel, diluent, or solvent).

FIG. 1 is a schematic diagram of a fuel cell based power generator 100in accordance with an embodiment of the present disclosure. In theembodiment shown in FIG. 1 , power generator 100 includes a fuel cell110 and a hydrogen generator 115.

As used herein, the term “fuel cell” can, for example, refer to anelectrochemical cell that converts chemical energy from a fuel intoelectricity through an electrochemical reaction. For example, hydrogencan be provided to fuel cell 110 such that hydrogen is consumed in anelectrochemical reaction to produce electricity, as is further describedherein. An ambient air path 120 is configured to run ambient air past acathode side of the fuel cell 110, via ambient air path portion 122. Theambient air path 120 is part of a cathode loop, which includes all thepaths that ambient air circulates through, including interiors ofcomponents the ambient air passes through.

A reaction in the fuel cell 110 generates electrical power and addswater as a by-product to the ambient air path portion 122. This water isthen provided to the hydrogen generator 115, which contains one or morefuels that release hydrogen responsive to exposure to water, which maybe in vapor form. As used herein, the term “hydrogen generator” refersto a device which contains one or more fuels that release hydrogenresponsive to exposure to water, which may be in the form of humidity.

The hydrogen generator 115 provides the released hydrogen to arecirculating hydrogen path 125, which splits into two parts at junction127. The two parts include a primary path 126 and a secondary path 128.The primary path 126 recirculates released hydrogen back to hydrogengenerator 115. The secondary path 128 runs past the anode side of thefuel cell 110 to provide the hydrogen to the fuel cell 110. Thesecondary path 128 is part of an anode loop, which includes all thepaths that hydrogen recirculates through, including interiors ofcomponents the ambient air passes through.

Hydrogen from the recirculating hydrogen path 125 reacts with oxygenfrom the ambient air path 120 in fuel cell 110, producing electricalpower, water vapor, and heat as reaction byproducts. The byproducts onthe cathode side of the fuel cell 110 are removed from the fuel cell bythe air flowing within ambient airflow path 120. Leftover hydrogen andany inert gases that leak/permeate into the anode loop over timecontinue through the recirculating hydrogen path 125.

In some embodiments, a cooling mechanism 132, such as a fan or liquidcooling loop, can be used with the fuel cell portion system to assist inthe removal of heat. In such an embodiment, most of the heat generatedin the fuel cell is removed via this liquid cooling loop and rejected toambient via a heat exchanger and/or fan, represented in block form aspart of the cooling mechanism 132.

In some embodiments, as shown in FIG. 1 , the secondary path 128 caninclude a purge valve 129 that purges inert gases (e.g. nitrogen, watervapor) that build up over time in the anode loop into an ambient airflowpath portion 123 of the ambient airflow path 120. These gases are purgedperiodically by actuating the purge valve 129, for example, based onpredetermined timing or a sensed parameter like fuel cell voltage orhydrogen concentration. In some embodiments, the valve may be slightlyopen most of the time to continuously remove the inert gases, with mostof the hydrogen flowing to and being consumed by the anode of the fuelcell.

In some embodiments, the fuel cells provide current to a controller 135that charges a Li-ion battery or batteries 130. The controller 135 alsoprovides power to a load, such as the UAS. In some implementations, thebatteries can provide the ability to supply higher and more dynamiclevels of power than simply utilizing the fuel cells directly, which canbe slower to respond and not normally be able to provide high levels ofpower that may be required for operation of the UAS in a desired manner,such as accelerating sufficiently while carrying a load.

Controller 135 may comprise a microprocessor, circuitry, and otherelectronics to receive data representative of sensed pressure,temperature, and other parameters and utilize control algorithms, suchas proportional/integral/derivative (PID) or other type of algorithms tocontrol mechanisms to modify the parameters to meet one or moredifferent setpoints. Controller 135 may also be referred to as a powermanagement module or controller 135. In some embodiments, control may bebased on proportional controller.

In some embodiments, the fuel cell based power generator 100 has asystem configuration (implemented in a X590 form factor battery packagein one embodiment) and its operating principle is schematically depictedin FIG. 1 . Hydrogen generator 115, in various embodiments, is areplaceable and disposable “fuel-cartridge” unit that generates H₂ for aH₂/oxygen proton exchange membrane (PEM) fuel cell 110, and a permanentunit that, in some embodiments, includes PEM fuel cell 110, Li-ionrecharge battery 130 as an output stage to interface with an externalload, and the controller 135 that controls electronic and fluidiccontrol circuits (e.g., controlling one or more fluid movementapparatuses) to dynamically sense and optimize the power generator 100under varying load and environmental conditions.

Ambient air serves as the fuel cell power generator 100 oxygen source,carrier gas for water vapor, and coolant gas for the fuel cell stack andH₂ generator. A first fluid movement apparatus (e.g., a fan) 140 drawsin fresh air from ambient via an inlet 142 and circulates it over thecathode side of the fuel cell stack at 121 via the ambient air path orpassage 120.

Since the fuel cell 110 reaction is exothermic, the temperature of thefuel cell 110 increases and may be measured by a first temperaturesensor 143 associated with fuel cell 110, which is positioned to measurethe temperature of the fuel cell 110. The temperature sensor is shown inblock form and may be placed anywhere such that it is thermally coupledto the fuel cell 110 to provide a reliable measurement of thetemperature of the fuel cell 110. Sensor 143 may comprise multipletemperature sensors. In one embodiment, one of the temperature sensorsis coupled to provide data representative of the temperature proximatethe anode, and another coupled to provide data representative of thetemperature proximate the cathode of the fuel cell 110. The temperaturedata is provided to the controller 135 for use in controlling to one ormore setpoints. A fuel cell set point temperature of the fuel cell 110is indicated as 60° C., which has been found to be a temperature atwhich the fuel cell 110 functions most efficiently.

In further embodiments, the set point may vary between 40° C. and 80°C., and may vary further depending on the configuration and specificmaterials utilized in fuel cell 110 and system 100. Different optimalset points for the fuel cell may be determined experimentally fordifferent fuel cells and may be found to be outside the range specifiedabove.

The fuel cell temperature is modified via cooling mechanism 132 (e.g.,liquid cooling loop with liquid pump, heat exchanger, and fan) undercontrol of controller 135 that receives temperature information fromfirst temperature sensor 143. The first temperature sensor 143 mayinclude separate temperature sensors to sense temperatures of both theanode side and cathode side of the fuel cell 110.

In some embodiments, the fuel cell temperature and hydrogen generatortemperature can be controlled separately. Separately controllable fansand or fluid pumps may be used for such independent control. The powermanagement module may control various pressures and temperatures via thevarious mechanisms using one or more of PID control, proportionalcontrol, or other type of algorithm. Temperatures may be controlledwithin desired temperature ranges defined by upper and lower temperaturethresholds.

While the fuel cell 110 is producing electrical power as well as heat,ambient air flowing within path 120 delivers oxygen to the fuel cell 110cathode and removes water vapor generated by the reaction in the fuelcell 110. The hot, humid air continues down path 120 to a first waterexchanger 155. The water exchanger 155 extracts water from the hot,humid ambient air and passes the extracted water into the hydrogen flowpath 124 (anode loop). The hot, somewhat drier air continues down path122′ to a second water exchanger 157, where heat and water is passedinto the cathode loop. This heat and water raise the temperature andhumidity of the incoming ambient air, which improves fuel cellperformance. After exiting the second water exchanger, the warm dry airis exhausted to the ambient at 160.

Water exchanger 155, and the operation of water exchanger 155, isfurther described herein. For instance, water exchanger 155 can be alight-weight, low pressure-drop water exchanger, as will be furtherdescribed herein.

The extracted water from the ambient air path is then provided to therecirculating hydrogen path to create humid hydrogen (H₂) at 124. Thishumid H₂ then flows to the hydrogen generator where water thereininteracts with the fuel to generate additional hydrogen.

The hydrogen generator 115 also has a set point temperature at which itoperates most efficiently. The temperature may be measured by sensingthe temperature of the hydrogen as it exits the hydrogen generator 115as represented by the position of a sensor 133, which may be atemperature sensor and also may include a pressure sensor. The hydrogengenerator experiences an exothermic reaction and has an optimaloperating set point is shown as 80° C., but may vary from 60° C.-100° C.or outside the range depending on the composition of the hydrogengenerator used.

The hydrogen generator temperature may be controlled by varying thespeed of one or more cooling mechanisms 131 positioned to remove heatfrom the hydrogen generator. The cooling mechanism may be positioned onthe outside of the hydrogen generator or positioned proximate thehydrogen generator to effect cooling of the hydrogen generator. Forexample, in some embodiments, the hydrogen generator temperature ismodified by an external cooling mechanism (e.g., a fan, blower, etc.)positioned, for instance, on the surface of the generator. The coolingmechanism may be controlled via the controller 135 using PID or othercontrol algorithms, such as proportional control. The hydrogen generatorcould also be cooled using a liquid cooling loop and associated liquidpump, heat exchanger, and fan.

The humid hydrogen 124 flows into the hydrogen generator 115, where thewater reacts with the fuel and generates hydrogen. The now dry hydrogenleaves the hydrogen generator and flows into blower 165, which raisesthe pressure.

The higher pressure dry hydrogen then progresses down the path 125 to asplit 127 where some of the dry H₂ enters a primary path 126 and somedry H₂ enters a secondary path 128.

The secondary path 128 is located adjacent the anode side of the fuelcell to provide hydrogen to the fuel cell, while the primary path can belocated further away from the fuel cell. This configuration allows for alarge amount of hydrogen to recirculate continuously through the systemin a hydrogen loop (to efficiently extract the water from the cathodevia the ambient air path water exchanger 155) while flowing a smalleramount of hydrogen to the fuel cell via secondary path 128.

The secondary path 128 can be a dead end with a purge valve 129 thereinthat allows inert gasses (e.g., nitrogen, water vapor) to be purged fromthe anode stream by actuating the valve periodically (e.g., based timingor a sensed parameter such as fuel cell voltage or oxygenconcentration). Because some water vapor is included in the inert gas,it is desirable to purge the inert gas into the cathode stream 122upstream of the primary water exchanger 155, so that the water vapor canbe recovered via water exchangers 155 and 157.

The anode loop pressure as measured by sensor 133 is controlled byvarying the blower 165 fan speed, which controls the amount of waterrecovered from through the water exchanger 155, and hydrogen generatedin the hydrogen generator 115. Higher blower fan speeds lead to higheranode loop pressures, for example, pressures slightly above ambientpressure by 1-10 psig.

Steady state operation of the fuel cell based power generator can beachieved by:

1) Controlling cathode blower speed based on power demand from load;

2) Controlling anode blower speed based on anode loop pressure (e.g.,measured via pressure sensor 133);

3) Controlling fuel cell cooling based on fuel cell temperature (e.g.,via cooling mechanism 132); and/or

4) Controlling pump/fan speed control for cooling mechanism 131 (e.g.,fan, blower, cooling loop, etc.) associated with the hydrogen generator(e.g., mounted on the outside of the hydrogen generator) based onhydrogen generator temperature.

In some embodiments, as air passes by the fuel cell stack 110 from theambient air path 120 and the secondary path 128 of the recirculatinghydrogen path 125, oxygen and hydrogen are consumed by the fuel cell110, and water vapor and waste heat are removed by the ambient air atfuel cell cathode 121.

The power generated in the fuel cell stack may be fed to controller 135which may include power management circuitry. The circuitry conditionsthe power and provides it as electricity to a load as indicated bycontacts 180.

One or more sensors may measure, in addition to the temperature sensorpreviously described, humidity, and/or pressure throughout the system100. Data provided by the sensors, as well as the electrical load and/orcharge state of the charge storage device 130 are used by the controlcontroller 135 to determine and set the various fluid movement apparatusspeeds to control the temperature of the elements to corresponding setpoints. Power management circuitry 135 can include a controller, as isfurther described herein.

Fuel consumption may also be monitored via controller 135 or other powermonitoring device, and the remaining capacity may be displayed via adisplay on the fuel cell power generator packaging as driven bycontroller 135 in various embodiments. In some embodiments, greater than95% fuel utilization may be achieved through an optimized LAH fuelformation (e.g., through one or more of porosity, particlesize/distribution, rate enhancing additives, or other formulationcharacteristics).

In some embodiments, the LAH-water reaction generates heat (˜150 kJ/molLAH, exothermic) leading to a rise in temperature in the fuel. Thetemperature may be monitored along with controlling the speed of thehydrogen generator cooling fan to maintain the temperature at a desiredset point for optimal operation.

Electrochemical system power performance can substantially degrade atlow temperatures (−40° C.) due to slower reaction kinetics and lowerelectrolyte conductivity. The hybrid fuel cell may avoid freezingproblems by: 1) using water in vapor form, 2) adjusting airflow toprevent water vapor condensation, 3) using heat generated by the fuelcell stack and H₂ generator to regulate their temperatures, 4)Insulating certain system components, and 5) using electrically powerheaters to control the temperature of certain system components. In someembodiments, noryl plastic packaging (e.g., consistent with the typeused on the Saft BA5590) may be used. Many different types of plasticsand/or other materials (e.g., that provide low weight yet sufficienttolerance to the operating parameters and environmental conditions ofthe generator) may be used.

Hydrogen generator 115 in some embodiments is a high-rate hydrogengenerator suitable for man-portable power and micro air vehicleapplications that provides four to five times the hydrogen ofcommercially available hydrogen sources of the same size and weight.Many different hydrogen producing fuels, such as LAH may be used. Infurther embodiments, the hydrogen producing fuel may, for example,include AlH₃, LiAlH₄, NaAlH₄, KAlH₄, MgAlH₄, CaH₂, LiBH₄, NaBH₄, LiH,MgH₂, Li₃Al₂, CaAl₂H₈, Mg₂Al₃, alkali metals, alkaline earth metals,alkali metal silicides, or combinations of one or more thereof.

The term “about” as used herein can allow for a degree of variability ina value or range, for example, within 10%, within 5%, or within 1% of astated value or of a stated limit of a range, and includes the exactstated value or range.

The term “substantially” as used herein refers to a majority of, ormostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%,98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or100%.

Hydrogen-Generating Composition for a Fuel Cell

In various embodiments, the present disclosure provides ahydrogen-generating composition for a fuel cell.

The hydrogen-generating composition reacts with water to generatehydrogen gas. The phase of the water contacted with thehydrogen-generating composition to generate the hydrogen gas can be anysuitable phase, such as liquid water (e.g., in a pure state, dilutedstate, or such as having one or more compounds or solvents dissolvedtherein) or gaseous water (e.g., water vapor, at any suitableconcentration). The generated hydrogen gas can be used as the fuel for ahydrogen-consuming fuel cell.

The hydrogen-generating composition can be in any suitable form. Thehydrogen-generating composition can, for example, be in the form of aloose powder or a compressed powder. The hydrogen-generating compositioncan also be in the form of grains or pellets (e.g., a powder or grainscompressed into pellets). The hydrogen- generating composition can haveany suitable density, such as, for example, about 0.5 g/cm³ to about 1.5g/cm³, or about 0.5 g/cm³ or less, or less than, equal to, or greaterthan about 0.6 g/cm³, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 g/cm³, orabout 1.5 g/cm³ or more.

In some embodiments, the hydrogen-generating composition issubstantially free of elemental metals. In some embodiments, thehydrogen-generating composition can be substantially free of elementalaluminum.

Hydride

The hydrogen-generating composition may include one or more hydrides.The one or more hydrides can form any suitable proportion of thehydrogen-generating composition, such as about 50 wt % to about 99.999wt %, about 70 wt % to about 99.9 wt %, about 70 wt % to about 90 wt %,or about 50 wt % or less, or less than, equal to, or greater than about52 wt %, 54, 56, 58, 60, 62, 64, 66, 68, 70, 71, 72, 73, 74, 75, 76, 77,78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 92, 94, 96, 98, 99,99.9, 99.99, or about 99.999 wt % or more.

The hydride can be any suitable hydride, such that thehydrogen-generating composition can be used as described herein. Thehydride can be a compound in which one or more hydrogen centers (e.g.,one or more hydrogen atoms, or a group that includes one or morehydrogen atoms) having nucleophilic, reducing, or basic properties.

The hydrogen atom in the hydride can be bonded to a more electropositiveelement or group. For example, the hydrogen can be chosen from an ionichydride (e.g., a hydrogen atom bound to an electropositive metal, suchas an alkali metal or alkaline earth metal), a covalent hydride (e.g.,compounds including covalently bonded hydrogen and that react ashydride, such that the hydrogen atom or hydrogen center has nucleophilicproperties, reducing properties, basic properties, or a combinationthereof), a metallic hydride (e.g., interstitial hydrides that existwithin metals or alloys), a transition metal hydride complex (e.g.,including compounds that can be classified as covalent hydrides orinterstitial hydrides, such as including a single bond between thehydrogen atom and a transition metal), or a combination thereof.

The hydride can be chosen from magnesium hydride (MgH₂), lithium hydride(LiH), aluminum hydride (AlH₃), calcium hydride (CaH₂), sodium aluminumhydride (NaAlH₄), sodium borohydride (NaBH₄), lithium aluminum hydride(LAlH₄), ammonia borane (H₃NBH₃), diborane (B₂H₆), palladium hydride,LaNi₅H₆, TiFeH₂, and a combination thereof. The hydride can be chosenfrom lithium aluminum hydride (LiAlH₄), calcium hydride (CaH₂), sodiumaluminum hydride (NaAlH₄), aluminum hydride (AlH₃), and a combinationthereof. The hydride can be lithium aluminum hydride (LiAlH₄).

In some embodiments, the hydrogen-generating composition only includes asingle hydride and is substantially free of other hydrides. In someembodiments, the hydrogen-generating composition only includes one ormore hydrides chosen from lithium aluminum hydride (LiAlH₄), calciumhydride (CaH₂), sodium aluminum hydride (NaAlH₄), and aluminum hydride(AlH₃), and is substantially free of other hydrides.

In various embodiments, the hydrogen-generating composition onlyincludes the hydride lithium aluminum hydride (LiAlH₄), and issubstantially free of other hydrides. In some embodiments, thehydrogen-generating composition can be substantially free of simplehydrides that are a metal atom directly bound to a hydrogen atom. Insome embodiments, the hydrogen-generating composition can besubstantially free of lithium hydride and beryllium hydride.

In various embodiments, the hydrogen-generating composition can besubstantially free of hydrides of aluminum (Al), arsenic (As), boron(B), barium (Ba), beryllium (Be), calcium (Ca), cadmium (Cd), cerium(Ce), cesium (Cs), copper (Cu), europium (Eu), iron (Fe), gallium (Ga),gadolinium (Gd), germanium (Ge), hafnium (Hf), mercury (Hg), indium(In), potassium (K), lanthanum (La), lithium (Li), magnesium (Mg),manganese (Mn), sodium (Na), neodymium (Nd), nickel (Ni), lead (Pb),praseodymium (Pr), rubidium (Rb), antimony (Sb), scandium (Sc), selenium(Se), silicon (Si), samarium (Sm), tin (Sn), strontium (Sr), thorium(Th), titanium (Ti), thallium (TI), vanadium (V), tungsten (W), yttrium(Y), ytterbium (Yb), zinc (Zn), zirconium (Zr), hydrides of organiccations including (CH₃) methyl groups, or a combination thereof. In someembodiments, the hydrogen-generating composition can be substantiallyfree of one or more of lithium hydride (LiH), sodium hydride (NaH),potassium hydride (KH), magnesium hydride (MgH₂), calcium hydride(CaH₂), lithium aluminum hydride (LiAlH₄), sodium borohydride (NaBH₄),lithium borohydride (LiBH₄), magnesium borohydride Mg(BH₄)₂, sodiumaluminum hydride (NaAlH₄), or mixtures thereof.

In various embodiments, the hydrogen-generating composition includes ametal hydride (e.g., an interstitial intermetallic hydride). Metalhydrides can reversibly absorb hydrogen into their metal lattice. Themetal hydride can be any suitable metal hydride.

The metal hydride can, for example, be LaNi₅, LaNi_(4.6)Mn_(0.4),MnNi_(3.5)Co_(0.7)Al_(0.8), MnNi_(4.2)Co_(0.2)Mn_(0.3)Al_(0.3),TiFe_(0.8)Ni_(0.2), CaNi₅, (V_(0.9)Ti_(0.1))_(0.95)Fe_(0.05),(V_(0.9)Ti_(0.1))_(0.95)Fe_(0.05), LaNi_(4.7)Al_(0.3), LaNi_(5-x)Al_(x)wherein x is about 0 to about 1, or any combination thereof. The metalhydride can be LaNi_(5-x)Al_(x) wherein x is about 0 to about 1 (e.g.,from LaNi₅ to LaNi₄Al). The metal hydride can form any suitableproportion of the hydrogen-generating composition, such as about 10 wt %to about 99.999 wt %, or about 20 wt % to about 99.5 wt %, or about 10wt % or less, or less than, equal to, or greater than about 15 wt %, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99,or about 99.999 wt % or more. Any metal hydride that is described inU.S. Pat. No. 8,172,928, incorporated by reference herein in itsentirety, can be included in the present hydrogen-generatingcomposition.

The hydrogen-generating composition can include both a metal hydride(e.g., an interstitial intermetallic hydride, such as LaNi_(5-x)Al_(x)wherein x is about 0 to about 1), and a chemical hydride (e.g., an ionichydride or a covalent hydride, such as magnesium hydride (MgH₂), lithiumhydride (LiH), aluminum hydride (AlH₃), calcium hydride (CaH₂), sodiumaluminum hydride (NaAlH₄), sodium borohydride (NaBH₄), lithium aluminumhydride (LiAlH₄), ammonia borane (H₃NBH₃), diborane (B₂H₆), palladiumhydride, LaNi₅H₆, TiFeH₂, and a combination thereof).

Metal Oxide

In various embodiments, the hydrogen-generating composition can includeone or more metal oxides. In some embodiments, the hydrogen-generatingcomposition can be free of metal oxides. The one or more metal oxidescan form any suitable proportion of the hydrogen-generating composition,such as about 0.001 wt % to about 20 wt % of the hydrogen-generatingcomposition, about 1 wt % to about 10 wt %, or about 0.001 wt % or less,or less than, equal to, or greater than about 0.01, 0.1, 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 12, 14, 16, 18, or about 20 wt % or more.

The metal oxide can be any suitable metal oxide, such that thehydrogen-generating composition can be used as described herein. Themetal oxide can be zirconium (IV) oxide, hafnium (IV) oxide, titanium(IV) oxide, or a combination thereof. The metal oxide can be titanium(IV) oxide.

The hydrogen-consuming fuel cell can include an anode, a cathode, and anelectrically-insulating ion-conducting electrolyte (e.g., a membrane,such as a proton exchange membrane, or PEM) separating the anode andcathode, wherein at least one of the anode or cathode undergoes achemical reaction that consumes hydrogen and generates an electricalpotential across the electrodes. In some embodiments, the cathode of thefuel cell consumes hydrogen gas and generates electrons and hydrogenions.

The hydrogen ions can travel across the electrolyte to the cathode,while the electrons can travel to the cathode via an electrical circuitconnecting the anode to the cathode. At the cathode, the hydrogen ionscan react with oxygen gas and the electrons produced by the anode toform water.

The water vapor reacts with the chemical hydride fuel in the hydrogengenerator, and generates hydrogen in an exothermic reaction. Thehydrogen is carried to a PEM fuel cell as illustrated in FIG. 1 togenerate electrical power.

The hydrogen generator 115 may be contained in a replaceable anddisposable (recyclable) cartridge such as a container. The hydrogengenerator 115 may be cylindrical in geometry in some embodiments.

During the electrochemical reaction in fuel cell 110 that producesenergy, water vapor, and heat as reaction byproducts, the ambient airwithin the path 120 is heated and water is added resulting in hot, wetair travelling through the path at 122.

The water exchanger 155 extracts water from the hot, wet air withinambient air path at 123, and exhausts hot, dry air outside the powergenerator 100 at exhaust 160. The set point temperature, which in someembodiments is 60° C., may, for example, vary from 40° C. to 80° C. insome embodiments, or outside that range depending on the type of waterexchanger utilized as first water exchanger 155. The extracted waterfrom the ambient air path 120 is provided to the anode loop 125 torelease additional hydrogen at 124 from hydrogen generator 115.Temperature sensors in the anode and cathode loops may be used todetermine and control the water exchanger 155 temperature. One or moresensors may be positioned proximate outlets of the water exchanger toprovide a temperature data to the controller 135.

As shown in the embodiment of FIG. 1 , the power generator 100 can alsoinclude one or more other water exchangers, such as second waterexchanger 157. Second water exchanger 157 transfers heat and water vaporto the incoming air at inlet 142, which improves fuel cell performance.In some embodiments a single water exchanger which combines thefunctions of the first and second water exchangers (e.g. has separateflow paths for the anode and cathode loops) is used to save weight.

Once the released hydrogen travels from hydrogen generator 115 throughanode loop 125, it progresses to junction 127 where some of the hydrogenenters a primary path 126 to be recirculated and some hydrogen enters asecondary path 128 to be provided for the electrochemical reaction infuel cell 110.

As described above, the electrochemical reaction in fuel cell 110 canproduce energy. In some embodiments, the fuel cell 110 charges a chargestorage device 130. The charge storage device can be a rechargeablebattery such as a lithium-ion battery, a capacitor, or any othersuitable charge storage device. In other words, charge storage device130 is coupled to power generator 100 such that charge storage device130 receives electricity generated by fuel cell 110.

In some implementations, the charge storage device 130 can provide theability to supply higher and more dynamic levels of power than simplyutilizing the fuel cell 110 directly, which can be slower to respond andnot normally be able to provide high levels of power that may berequired for operation of a UAS in a desired manner, such asaccelerating sufficiently while carrying a load. In the embodiment ofFIG. 1 , power generated by the fuel cell 110 can be provided forstorage in one or more charge storage devices 130, and/or provideddirectly to the load from the controller 135.

As illustrated in FIG. 1 , power generator 100 can include controller135. Controller 135 can provide inputs to power generator 100 such thatpower generator 100 can run optimally, producing power to be stored incharge storage device 130 for use by a UAS, for example. For example,controller/power management electronics can manage flow of power fromthe fuel cell to the load, and/or control other aspects of powergeneration (e.g., regulation of temperatures, pressures, flow rates,etc.)

Controller 135 can provide inputs to power generator 100 in various wayssuch that power generator 100 can optimally generate power, as arefurther described herein. For example, in some embodiments, controller135 can provide inputs to power generator 100 based on a pressure inanode loop 125. In some embodiments, controller 135 can provide inputsto power generator 100 based on a current draw by the load (e.g., a UAS)from charge storage device 130. However, embodiments of the presentdisclosure are not limited to control schemes for power generator 100.For example, controller 135 can provide inputs for other systemcontrols. For instance, controller 135 can control the temperature ofthe fuel cell/hydrogen generator, pressure in the anode loop, flow inanode and cathode loops, state of charge of charge storage device,anticipated changes in load from the device the power source ispowering, etc.

As described above, in some examples controller 135 can provide inputsto power generator 100 based on a pressure in anode loop 125. Controller135 can receive a pressure reading in anode loop 125, where the pressurein anode loop 125 is based on the blower fan speed of blower 165.

The pressure reading received by controller 135 can be the pressure inanode loop 126. The pressure in anode loop 126 can be the absolutepressure or the gauge pressure relative to the local ambient pressure.For example, a sensor included in anode loop 125 can determine thepressure in anode loop 125 and transmit the pressure to controller 135.The pressure in anode loop 126 can allow controller 135 to determine aspeed of blower 165 in order to allow hydrogen generator 115, fuel cell110, first water exchanger 155 and/or second water exchanger 157 tooperate optimally, as is further described herein. That is, the speed ofblower 165 can affect operating parameters of the hydrogen generator115, fuel cell 110, first water exchanger 155 and/or second waterexchanger 157 according to the operational scheme of power generator 100as described above.

Controller 135 can determine whether the pressure in anode loop 125exceeds a threshold pressure. As an example, the sensor in anode loop125 can determine the pressure in anode loop 125 is 8 pounds per squareinch (PSI). Controller 135 can compare the received pressure to athreshold pressure to determine whether the received pressure exceedsthe threshold pressure. The threshold pressure can be a predeterminedpressure stored locally in memory included in controller 135.

The threshold pressure can be a pressure range. For example, thepressure range can include an upper threshold pressure and a lowerthreshold pressure. For instance, operation of power generator 100 mayoccur optimally at a particular pressure of the anode loop 125, and theparticular pressure of the anode loop 125 can fall within the thresholdpressure range. That is, the particular pressure of the anode loop 125can be within the lower threshold pressure and the upper thresholdpressure.

In some examples, controller 135 can determine the pressure in anodeloop 125 is less than the lower threshold pressure. For example, thelower threshold pressure can be 5 PSI, and the controller 135 candetermine the received pressure in the anode loop 125 is 4 PSI.Accordingly, controller 135 can determine the pressure in anode loop 125is less than the lower threshold pressure.

A drop in pressure in anode loop 125 can, in some examples, correspondto a higher power requirement by the load from charge storage device130. For example, in response to more power being drawn by the load(e.g., by a UAS), more energy from fuel cell 110 may be needed to meetthe demand. As the rate of hydrogen being used by fuel cell 110increases to generate more energy, the pressure in anode loop 125 candrop, causing the pressure to fall below the lower threshold pressure.

In order to compensate for the rate of hydrogen being utilized by fuelcell 110 from hydrogen generator 115 increasing as a result of theincreased load from the UAS, controller 135 can modify the speed ofblower 165 to increase the hydrogen generation rate in the hydrogengenerator. Controller 135 can modify the speed of blower 165 byincreasing the blower speed such that blower 165 can provide more watervapor to the hydrogen generator 115, which increases the hydrogengeneration rate. Increasing the speed of blower 165 thus increases thepressure in anode loop 125 (e.g., to within the threshold pressure rangeas described above). As a result, operational parameters for variouscomponents of power generator 100 can be kept to within idealoperational limits.

In some examples, controller 135 can determine the pressure in anodeloop 125 exceeds the upper threshold pressure. For example, the upperthreshold pressure can be 12 PSI, and the controller 135 can determinethe received pressure in the anode loop 125 is 14 PSI. Accordingly,controller 135 can determine the pressure in anode loop 125 has exceededthe upper threshold pressure.

An increase in pressure in anode loop 125 can, in some examples,correspond to a lower power requirement by the load or the chargestorage device 130. For example, in response to lower power being usedby the load (e.g., by a UAS) or by charge storage device 130, power maybe required from fuel cell 110. As the rate of hydrogen being used byfuel cell 110 decreases to generate less power for charge storage device130, the pressure in anode loop 125 can increase, causing the pressureto increase above the higher threshold pressure.

In order to compensate for the rate of hydrogen being utilized by fuelcell 110 from hydrogen generator 115 decreasing as a result of thedecreased load from the UAS or charge storage device 130, controller 135can modify the speed of blower 165. Controller 135 can modify the speedof blower 165 by decreasing the blower speed such that blower 165 canprovide less water vapor to hydrogen generator 115, which decreases thehydrogen generation rate. Decreasing the speed of blower 165 cancorrespondingly decrease the pressure in anode loop 125 (e.g., to withinthe threshold pressure range as described above). As a result,operational parameters for various components of power generator 100 canbe kept to within ideal operational limits.

Although the lower threshold pressure is described above as being 5 PSIand the upper threshold pressure is described above as being 14 PSI,embodiments of the present disclosure are not so limited. For example,the upper and lower threshold pressures can be any other pressure value.In some examples, the pressure values of the upper and lower thresholdpressures can vary based on the load (e.g., the UAS), the type ofhydrogen fuel utilized by hydrogen generator 115, among otherparameters.

As described above, modifying the speed of blower 165 can affectoperating parameters of various components of power generator 100. Forexample, modifying the speed of blower 165 to modify the pressure inanode loop 125 can maintain an inlet and outlet relative humidity offuel cell 110 within a predetermined range, maintain an inlet and outletrelative humidity of hydrogen generator 115 within a predeterminedrange, maintain an inlet and outlet relative humidity of first waterexchanger 155 and/or second water exchanger 155 within a predeterminedrange, and/or a temperature of first water exchanger 155 and/or secondwater exchanger 155 within a predetermined range, among other operatingparameters and/or other operating parameters of other components ofpower generator 100.

Various sensors can be utilized to monitor components of power generator100. For example, the various components of power generator 100 caninclude temperature sensors that can transmit temperatures of hydrogengenerator 115, fuel cell 110, and/or first water exchanger 155 and/orsecond water exchanger 157 to controller 135. In some examples,controller 135 can maintain operating temperatures of the hydrogengenerator 115, fuel cell 110, and/or first water exchanger 155 and/orsecond water exchanger 157 utilizing a fan and/or fans (e.g., operationof the fan/fans can lower the operating temperatures). In some examples,controller 135 can maintain operating temperatures of the hydrogengenerator 115, fuel cell 110, and/or first water exchanger 155 and/orsecond water exchanger 157 utilizing a pump circulating cooling fluid tothe components of power generator 100 (e.g., operation of the pumpcirculating the cooling fluid can lower the operating temperatures).

As described above, in some examples controller 135 can provide inputsto power generator 100 based on a current draw by the load (e.g., a UAS)from charge storage device 130. Controller 135 can receive an amount ofcurrent draw from charge storage device 130 coupled to fuel cell 110. Asdescribed above, the charge storage device 130 receives electricitygenerated by fuel cell 110 in response to hydrogen being provided to ananode of fuel cell 110. Hydrogen can be supplied to the anode via blower165 by way of anode loop 125 and secondary path 128.

The current draw from charge storage device 130 can be by the load inaddition to that drawn by controller 135 and the mechanisms controlledby controller 135. For example, a UAS may be drawing current from chargestorage device 130 in order to operate. The current draw from chargestorage device 130 can be measured by a sensor. For example, a currentsensor can measure the current from charge storage device 130 to theload and transmit the current to controller 135.

Controller 135 can determine whether the current draw from chargestorage device 130 exceeds a threshold current draw. As an example, thecurrent sensor can determine the current draw from charge storage device130 to be 50 A. Controller 135 can compare the received current draw toa threshold current draw to determine whether the received current drawexceeds the threshold current draw.

The threshold current draw can be a predetermined current draw storedlocally in memory included in controller 135.

The threshold current draw can be a current draw range. For example, thecurrent draw range can include an upper threshold current draw and alower threshold current draw.

In some examples, controller 135 can determine the current draw fromcharge storage device 130 exceeds the upper threshold current draw. Forexample, the upper threshold current draw can be 55 A, and thecontroller 135 can determine the current draw from charge storage device130 is 60 A. Accordingly, controller 135 can determine the current drawfrom charge storage device 130 exceeds the upper threshold current draw.An increase in current draw from charge storage device 130 can indicatethe load (e.g., the UAS) is utilizing more power.

In order to compensate for the increase in current draw by the load fromcharge storage device 130, controller 135 can modify the speed ofblowers 165 and 140. Controller 135 can modify the speed of blowers 165and 140 to provide more hydrogen from hydrogen generator 115 and airfrom ambient to fuel cell 110 by increasing a blower fan speed ofblowers 165 and 140. As a result of more hydrogen and air being providedto fuel cell 110, fuel cell 110 can generate more electricity to provideto charge storage device 130 to compensate for the increase in power bythe UAS so the UAS can continue to operate.

In some examples, controller 135 can determine the current draw fromcharge storage device 130 is less than the lower threshold current draw.For example, the lower threshold current draw can be 35 A. In anexample, the controller 135 may determine the current draw from chargestorage device 130 is 30 A. Accordingly, controller 135 can determinethe current draw from charge storage device 130 (e.g., 30 A) is lessthan the threshold current draw (e.g., 35 A). The decrease in currentdraw from charge storage device 130 can indicate the load (e.g., theUAS) is utilizing less power.

In order to compensate for the decrease in current draw by the load fromcharge storage device 130, controller 135 can modify the speed ofblowers 165 and 140. Controller 135 can modify the speed of blowers 165and 140 to provide less hydrogen from hydrogen generator 115 and airfrom ambient to fuel cell 110 by reducing a blower fan speed of blowers165 and 140. As a result of less hydrogen and air being provided to fuelcell 110, fuel cell 110 can generate less electricity to provide tocharge storage device 130.

Although the upper threshold current draw is described above as being 55A and the lower threshold current draw is described above as being 35 A,embodiments of the present disclosure are not so limited. For example,the upper and lower threshold current draws can be any other currentvalues.

The controller 135 may use PID type control algorithms to control thespeed of blowers 165 and 140 to maintain the operating parameters of thevarious components of power generator 100. Other control algorithms maybe used in further embodiments, such as modeling and any other type ofalgorithm sufficient to control the operating parameters of the variouscomponents of power generator 100 by controlling the speed of blowers165 and 140.

FIG. 2 is a perspective view of an unmanned air system (UAS)illustrating an open compartment according to embodiments of the presentdisclosure. In the embodiment illustrated in FIG. 2 , the compartment212 provides space and cooling for fuel cell based power generatorintegration. The fuel cell based power generator can provide powerresulting in a virtually silent long endurance ISR platform withoutstanding capability and stability. The use of the power generatorwith batteries charged from the fuel cell can provide rates ofelectrical power suitable for the above functions. Multiple functionscombined with long endurance provides maximum operational value andflexibility.

FIG. 3 is a method for fuel cell based power generation according toembodiments of the present disclosure. The method 372 can be performedby a power generator such as power generator 100, previously describedin connection with FIG. 1 . For example, the power generator can includea controller to control various operating parameters of the powergenerator. For instance, a controller may control a first coolingmechanism to control the temperature of a fuel cell of the powergenerator and control a second cooling mechanism to control thetemperature of a hydrogen generator of the power generator. Further, thecontroller can control the speed of various blowers to maintain otheroperating parameters of various components of the power generator, suchas a speed of a cathode blower based on power demand of the powergenerator and a speed of an anode blower based on pressure in an anodeloop of the power generator.

Prior to performing method 372, the power generator may be started up.Startup of the power generator can include pre-heating the fuel cellbased power generator, as is described herein.

In some examples, pre-heating the fuel cell based power generator duringstartup can include heating the fuel cell via heater tape. Heating thefuel cell via heater tape can cause the fuel cell to be heated up to itsoperating temperature. Heating the fuel cell via heater tape can allowthe fuel cell to be pre-heated to the range of operating temperatures orto a particular temperature in the range of operating temperatures.

An external power source may be utilized to provide power to the heatertape to cause the heater tape to heat the fuel cell to its operatingtemperature. However, embodiments of the present disclosure are not solimited. For example, a power source such as the charge storage devicemay be used to provide power to the heater tape.

Although pre-heating the fuel cell is described above as using heatertape, embodiments of the present disclosure are not so limited. Forexample, the fuel cell may be pre-heated using any other heating device.

During startup of the fuel cell based power generator, it can beimportant to have hydrogen present in the anode loop to allow for theelectrochemical reaction in the fuel cell to begin. Accordingly, in someexamples an external hydrogen gas tank may be connected to the anodeloop. The external hydrogen tank can fill the anode loop with hydrogenduring startup of the fuel cell based power generator. A purge valve(e.g., purge valve 129) can purge inert gases that may be located in theanode loop from the anode loop. The inlet connection for the hydrogengas tank and the purge valve can open alternatively to purge inert gasesfrom the anode loop while the inlet connection allows hydrogen gas intothe anode loop. As illustrated in FIG. 1 , the purge valve can belocated on an exit of the secondary path of the anode loop.

In some examples, pre-heating the fuel cell based power generator duringstartup can include turning on, by the controller previously describedin connection with FIG. 1 , an anode blower and a cathode blower. Theanode blower can cause hydrogen to be provided to the anode of the fuelcell and the cathode blower can cause ambient air to be provided to thecathode of the fuel cell. In some examples, as described above, thehydrogen provided to the anode can be from an external hydrogen gas tankconnected to the anode loop. In some examples, the hydrogen can be fromthe hydrogen generator of the anode loop. Hydrogen in the anode andambient air in the cathode can cause the fuel reaction process to beginin the fuel cell such that the fuel cell generates heat (e.g., as aresult of the electrochemical reaction in the fuel cell) to heat thefuel cell to its operating temperature or to a temperature in itsoperating temperature range.

In some examples, the fuel cell based power generator can be startedwith inert gases in it. Hydrogen can be provided to the anode of thefuel cell. As hydrogen is provided to the anode of the fuel cell (e.g.,by the hydrogen generator), purge valves (e.g., purge valve 129, a purgevalve located on the primary path 126 of the anode loop, and/or a purgevalve located in the ambient air path 120) can purge the inert gasesfrom the fuel cell based power generator during startup of the fuel cellbased power generator such that the fuel reaction process begins in thefuel cell to cause the fuel cell to begin to generate electricity.

Method 372 is a method for fuel cell based power generation. At 374,method 372 can include providing hydrogen to an anode of a fuel cell viaan anode loop connected to the fuel cell and a blower in the anode loopsuch that the fuel cell generates an amount of electricity. The hydrogencan be provided to the anode via a hydrogen generator. The hydrogengenerator can be located in the anode loop such that the blower(controlled by the controller) causes hydrogen generated by the hydrogengenerator to be provided to the anode of the fuel cell.

Ambient air can be provided to a cathode of the fuel cell. Ambient aircan be provided to the cathode via a blower (controlled by thecontroller) and blower inlet. The ambient air in the cathode and thehydrogen in the anode can cause an electrochemical reaction in the fuelcell which can result in production of energy, water vapor, and heat.The energy can be supplied to a charge storage device for use by a load,such as a UAS.

Maintaining a steady state operation of the fuel cell based powergenerator can allow for electricity to be provided to the load via thecharge storage device. For example, a UAS can utilize electricity fromthe charge storage device to maintain flight times greater than those oflithium ion/polymer batteries. A controller of the fuel cell based powergenerator can maintain steady state operation of the fuel cell basedpower generator, as is further described herein.

At 376, the method 372 includes receiving, by the controller, a pressurein the anode loop of the fuel cell based power generator. For example, asensor included in the anode loop can determine the pressure in anodeloop and transmit the pressure to the controller.

At 378, the method 372 includes determining, by the controller, whetherthe pressure in the anode loop exceeds an upper threshold pressure or alower threshold pressure. The upper threshold pressure and the lowerthreshold pressure can define a range of operating pressures of theanode loop. If the determined pressure in the anode loop exceeds theupper or lower threshold pressure, the controller can modify an input tothe fuel cell based power generator to maintain steady state operation,as is further described herein.

The controller can increase the speed of a blower of the anode loop inresponse to the pressure of the anode loop exceeding the lower thresholdpressure. For instance, a drop in pressure in the anode loop can, insome examples, correspond to a higher power requirement by the load fromthe charge storage device, causing the rate of hydrogen being used bythe fuel cell to increase to generate more energy for the charge storagedevice which can cause the pressure in the anode loop to drop, causingthe pressure to fall below the lower threshold pressure. In response,the controller can increase the speed of the blower to provide morehydrogen from the hydrogen generator to the fuel cell, increasing thepressure in the anode loop.

The controller can decrease the speed of the blower in the anode loop inresponse to the pressure of the anode loop exceeding the upper thresholdpressure. For instance, a rise in pressure in the anode loop can, insome examples, correspond to a lower power requirement by the load fromthe charge storage device, causing the rate of hydrogen being used bythe fuel cell to decrease to generate less energy for the charge storagedevice which can cause the pressure in the anode loop to rise, causingthe pressure to rise above the upper threshold pressure. In response,the controller can decrease the speed of the blower to provide lesshydrogen from the hydrogen generator to the fuel cell, decreasing thepressure in the anode loop.

At 382, the method 372 includes providing the amount of electricity to acharge storage device connected to the fuel cell. For example,electricity generated by the fuel cell by the electrochemical reactionof hydrogen in the anode and ambient air in the cathode can be providedto the charge storage device for use by a load, such as by a UAS.

The hydrogen generator can include a fuel cartridge. The fuel cartridgecan include the hydrogen to be provided to the fuel cell. Duringoperation of the fuel cell based power generator, the hydrogen generatorcan utilize an amount of hydrogen such that the fuel cartridge can runout of hydrogen. Accordingly, the fuel cartridge can be replaced.

Replacing a fuel cartridge of the hydrogen generator can includeremoving a spent fuel cartridge from the hydrogen generator. Removingthe spent fuel cartridge from the hydrogen generator can mechanicallyclose an inlet valve and an outlet valve of the hydrogen generator. Manydifferent types of valves may be used. In one embodiment, largeconductance valves, such as butterfly, gate, and iris valves may beused. Closing the inlet and outlet valves of the hydrogen generator canprevent ambient air and/or recirculating hydrogen in the anode loop frombeing provided to the anode of the fuel cell.

Replacing the fuel cartridge of the hydrogen generator can furtherinclude installing a new fuel cartridge in the hydrogen generator.Installing the new fuel cartridge can mechanically open the inlet valveand the outlet valve of the hydrogen generator, which can again allowfor hydrogen to be provided to the anode of the fuel cell via a blowerby way of the anode loop.

Embodiments of the present disclosure provide many benefits overprevious systems. For example, embodiments are disclosed herein thatreduce the weight of the fuel cell based power generator by reducing anamount of components, reducing fuel supplies, reducing by productsand/or leftover materials that may need to stay with the UAS during UASoperation, among other benefits described herein and understood fromreading this disclosure.

FIG. 4 is a schematic block diagram of an example controller for fuelcell based power generation according to embodiments of the presentdisclosure. As illustrated in FIG. 4 , controller 470 can include amemory 486 and a processor 484 for fuel cell based power generation inaccordance with the present disclosure.

The memory 486 can be any type of storage medium that can be accessed bythe processor 484 to perform various examples of the present disclosure.For example, the memory 486 can be a non-transitory computer readablemedium having computer readable instructions (e.g., computer programinstructions) stored thereon that are executable by the processor 484for fuel cell based power generation in accordance with the presentdisclosure.

The memory 486 can be volatile or nonvolatile memory. The memory 486 canalso be removable (e.g., portable) memory, or non-removable (e.g.,internal) memory. For example, the memory 486 can be random accessmemory (RAM) (e.g., dynamic random access memory (DRAM) and/or phasechange random access memory (PCRAM)), read-only memory (ROM) (e.g.,electrically erasable programmable read-only memory (EEPROM) and/orcompact-disc read-only memory (CD-ROM)), flash memory, a laser disc, adigital versatile disc (DVD) or other optical storage, and/or a magneticmedium such as magnetic cassettes, tapes, or disks, among other types ofmemory.

Further, although memory 486 is illustrated as being located withincontroller 470, embodiments of the present disclosure are not solimited. For example, memory 486 can also be located internal to anothercomputing resource (e.g., enabling computer readable instructions to bedownloaded over the Internet or another wired or wireless connection).

EXAMPLES

1. A controller for a fuel cell based power generator includes a memoryand a processor configured to execute executable instructions stored inthe memory to receive a pressure in an anode loop of the fuel cell basedpower generator, wherein the anode loop includes a hydrogen generatorand an anode loop blower, and control the anode loop blower such thatthe hydrogen generator provides hydrogen to an anode of a fuel cell viathe blower and the anode loop at a controlled pressure.

2. The controller of example 1 wherein the processor is furtherconfigured to execute the instructions to determine whether the pressurein the anode loop exceeds a threshold pressure and modify a speed of theanode loop blower to modify the pressure in the anode loop in responseto the determination.

3. The controller of example 2, wherein the processor is configured toexecute the instructions to determine whether the pressure in the anodeloop exceeds a lower threshold pressure and wherein the instructions tomodify the speed of the anode loop blower include instructions toincrease the speed of the blower in response to the pressure in theanode loop exceeding the lower threshold pressure.

4. The controller of any of examples 1-3, wherein the processor isconfigured to execute the instructions to determine whether the pressurein the anode loop exceeds an upper threshold pressure and wherein theinstructions to modify the speed of the anode loop blower includeinstructions to decrease the speed of the blower in response to thepressure in the anode loop exceeding the upper threshold pressure.

5. The controller of any of examples 1-4, and further including a chargestorage device coupled to the fuel cell such that the charge storagedevice receives electricity generated by the fuel cell and wherein theprocessor is configured to execute the instructions to modify the speedof the anode loop blower an amount of hydrogen provided to the anode ofthe fuel cell such that the electricity generated by the fuel cell andprovided to the charge storage device is modified.

6. The controller of any of examples 1-5, wherein the controllercontrols a first cooling mechanism to maintain a temperature within thefuel cell within a predetermined temperature range.

7. The controller of any of examples 1-6, wherein the controllercontrols a second cooling mechanism to maintain a temperature within thehydrogen generator within a predetermined temperature range.

8. The controller of any of examples 1-7, and further including a chargestorage device coupled to the fuel cell and wherein the processor isconfigured to execute the instructions to receive an amount of currentdraw from the charge storage device, wherein the charge storage devicereceives electricity generated by the fuel cell in response to hydrogenbeing provided to an anode of the fuel cell via the anode loop, and airbeing provided via a cathode loop blower and a cathode loop of the fuelcell based power generator, determine whether the current draw from thecharge storage device exceeds a threshold current draw, and modify aspeed of the blower to modify the pressure in the anode loop in responseto the determination.

9. The controller of any of examples 1-8 wherein the processor isconfigured to execute the instructions to receive values representativeof a hydrogen fuel generator temperature and a fuel cell temperature,and independently control the hydrogen fuel generator temperature andthe fuel cell temperature based on the received values.

10. A controller for a fuel cell based power generator, including amemory and a processor configured to execute executable instructionsstored in the memory to receive a current draw value representative ofan amount of current draw from a charge storage device coupled to a fuelcell, wherein the charge storage device receives electricity generatedby the fuel cell in response to hydrogen being provided to an anode ofthe fuel cell via an anode loop blower and an anode loop, and modify aspeed of the blower to modify the pressure in the anode loop in responseto the current draw value.

11. The controller of example 10, wherein the processor is configured toexecute the instructions to determine whether the current draw valueexceeds an upper threshold current draw value.

12. The controller of example 11, wherein the instructions to modify thespeed of the blower include instructions to increase the speed of theblower in response to the current draw value exceeding the upperthreshold current draw value.

13. The controller of any of examples 10-12, wherein the processor isconfigured to execute the instructions to determine whether current drawvalue is less than a lower threshold current draw value.

14. The controller of example 13, wherein the instructions to modify thespeed of the blower include instructions to decrease the speed of theblower in response to the current draw value being less than the lowerthreshold current draw value.

15. A method of operating a fuel cell based power generator includingproviding, by a hydrogen generator, hydrogen to an anode of a fuel cellvia an anode loop connected to the fuel cell and an anode loop blower inthe anode loop such that the fuel cell generates an amount ofelectricity, receiving a pressure value in the anode loop, andcontrolling the anode loop blower such that the hydrogen generatorprovides hydrogen to an anode of a fuel cell via the blower and theanode loop at a controlled pressure.

16. The method of example 15 and further including determining whetherthe pressure value in the anode loop exceeds an upper threshold pressurevalue or a lower threshold pressure value, modifying, by the controller,a speed of the anode blower by increasing the speed of an anode loopblower in response to the pressure value in the anode loop exceeding thelower threshold pressure value and decreasing the speed of the anodeloop blower in response to the pressure value in the anode loopexceeding the upper threshold pressure value, and providing, by the fuelcell, the amount of electricity to a charge storage device coupled tothe fuel cell.

17. The method of any of examples 15-16, wherein the method furtherincludes replacing a fuel cartridge of the hydrogen generator byremoving a fuel cartridge of the hydrogen generator, wherein removingthe fuel cartridge mechanically closes an inlet valve and an outletvalve of the hydrogen generator.

18. The method of example 17, wherein replacing the fuel cartridge ofthe hydrogen generator further includes installing a new fuel cartridgein the hydrogen generator, wherein installing the new fuel cartridgemechanically opens the inlet valve and the outlet valve of the hydrogengenerator.

19. The method of any of examples 15-18, wherein the method furtherincludes pre-heating the fuel cell based power generator during startupof the fuel cell based power generator by heating the fuel cell viaheater tape such that the fuel cell is heated to its operatingtemperature or turning on, by the controller, the anode loop blower anda cathode loop blower to provide hydrogen to the anode of the fuel cellsuch that a fuel reaction process begins in the fuel cell that generatesheat to heat the fuel cell to its operating temperature.

20. The method of any of examples 15-19, wherein the method furtherincludes filling the anode loop with hydrogen gas via an externalhydrogen tank connected to the anode loop during startup of the fuelcell based power generator, and purging, via a purge valve located onthe anode loop and a purge valve located on an the anode loop, inert gasfrom the anode loop while the hydrogen gas from the external hydrogentank fills the anode loop during the startup as the fuel cell begins togenerate the amount of electricity.

21. The method of any of examples 15-20, wherein the method furtherincludes purging, via a purge valve located on the anode loop and apurge valve located on an anode exit of the fuel cell, inert gases fromthe fuel cell based power generator during startup of the fuel cellbased power generator as hydrogen is provided to the anode of the fuelcell such that a fuel reaction process begins in the fuel cell to causethe fuel cell to begin to generate the amount of electricity.

22. The method of any of examples 15-21, wherein the method includescontrolling a speed of a cathode blower to provide ambient air to acathode of the fuel cell in order to maintain a steady power output fromthe fuel cell based on a power demand of a load connected to the chargestorage device.

23. The method of any of examples 15-22, wherein the method includesmaintaining an operating temperature of components of the fuel cellbased power generator by a temperature sensor associated with thecomponents of the fuel cell based power generator and a fan, wherein thecomponents of the fuel cell based power generator include at least oneof the hydrogen generator, the fuel cell, and a water exchanger.

24. The method of any of examples 15-23, wherein the method includesmaintaining an operating temperature of components of the fuel cellbased power generator by a temperature sensor associated with thecomponents of the fuel cell based power generator and a pump circulatingcooling fluid to the components of the fuel cell based power generator,wherein the components of the fuel cell based power generator include atleast one of the hydrogen generator, the fuel cell, and a waterexchanger.

25. A controller for a fuel cell based power generator including amemory and a processor configured to execute executable instructionsstored in the memory to receive values of parameters representative ofat least one of ambient air path pressure, hydrogen path pressure,hydrogen fuel generator temperature, fuel cell temperature, and loadcurrent, and independently control the hydrogen fuel generatortemperature and the fuel cell temperature based on the received values.

26. The controller of example 25 wherein the instructions are furtherexecuted to modify a speed of at least one blower to modify at least oneof the hydrogen fuel generator temperature and the fuel celltemperature.

27. A power generator including a fuel cell having a cathode and ananode, a controller coupled to receive electrical current generated bythe fuel cell, an anode loop coupled to the anode of the fuel cell, acathode loop coupled to the cathode of the fuel cell and to an oxygenand water source to provide oxygen to the cathode, a hydrogen generatorcoupled to provide hydrogen to the anode loop, a water exchanger coupledto the anode loop and the cathode loop to provide water from the cathodeloop to the anode loop, an anode loop pressure sensor coupled to provideanode loop pressure values to the controller, and an anode loop blowercoupled to the controller to control the anode loop blower speed as afunction of the anode loop pressure.

28. The power generator of example 27 and further including a fuel celltemperature sensor coupled to provide fuel cell temperature values tothe controller, a hydrogen generator temperature sensor to providehydrogen generator temperature values to the controller, a fuel cellcooling mechanism coupled to modify the fuel cell temperature undercontrol of the controller as a function of the fuel cell temperaturevalue, and a hydrogen generator temperature cooling mechanism coupled tomodify the hydrogen generator temperature under control of thecontroller as a function of the hydrogen generator temperature value.

29. The power generator of any of examples 27-28 wherein the waterexchanger temperature is a controlled by the controller as a function ofone or more of the fuel cell temperature and hydrogen generatortemperature values.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anyarrangement calculated to achieve the same techniques can be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments of thedisclosure.

It is to be understood that the above description has been made in anillustrative fashion, and not a restrictive one. Combination of theabove embodiments, and other embodiments not specifically describedherein will be apparent to those of skill in the art upon reviewing theabove description.

What is claimed:
 1. A method of operating a fuel cell based powergenerator, comprising: providing, by a hydrogen generator, hydrogen toan anode of a fuel cell via an anode loop connected to the fuel cell andan anode loop blower in the anode loop such that the fuel cell generatesan amount of electricity; receiving a pressure value in the anode loop;and controlling the anode loop blower such that the hydrogen generatorprovides hydrogen to an anode of a fuel cell via the blower and theanode loop at a controlled pressure
 2. The method of claim 1 and furthercomprising: determining whether the pressure value in the anode loopexceeds an upper threshold pressure value or a lower threshold pressurevalue; modifying, by the controller, a speed of the anode blower by:increasing the speed of an anode loop blower in response to the pressurevalue in the anode loop exceeding the lower threshold pressure value;and decreasing the speed of the anode loop blower in response to thepressure value in the anode loop exceeding the upper threshold pressurevalue; and providing, by the fuel cell, the amount of electricity to acharge storage device coupled to the fuel cell.
 3. The method of claim1, wherein the method further includes replacing a fuel cartridge of thehydrogen generator by removing a fuel cartridge of the hydrogengenerator, wherein removing the fuel cartridge mechanically closes aninlet valve and an outlet valve of the hydrogen generator.
 4. The methodof claim 3, wherein replacing the fuel cartridge of the hydrogengenerator further includes installing a new fuel cartridge in thehydrogen generator, wherein installing the new fuel cartridgemechanically opens the inlet valve and the outlet valve of the hydrogengenerator.
 5. The method of claim 1, wherein the method further includespre-heating the fuel cell based power generator during startup of thefuel cell based power generator by: heating the fuel cell via heatertape such that the fuel cell is heated to its operating temperature; orturning on, by the controller, the anode loop blower and a cathode loopblower to provide hydrogen to the anode of the fuel cell such that afuel reaction process begins in the fuel cell that generates heat toheat the fuel cell to its operating temperature.
 6. The method of claim1, wherein the method further includes: filling the anode loop withhydrogen gas via an external hydrogen tank connected to the anode loopduring startup of the fuel cell based power generator; and purging, viaa purge valve located on the anode loop and a purge valve located on theanode loop, inert gas from the anode loop while the hydrogen gas fromthe external hydrogen tank fills the anode loop during the startup asthe fuel cell begins to generate the amount of electricity.
 7. Acomputer implemented method comprising: receiving a pressure value ofsensed pressure in an anode loop of the fuel cell based power generator,wherein the anode loop includes a hydrogen generator that receiveshydrogen containing water from the anode loop and an anode loop blower;and controlling an anode loop blower speed such that the hydrogengenerator generates hydrogen in response to receiving the hydrogencontaining water and provides the hydrogen to an anode of a fuel cellvia the anode loop blower and the anode loop at a controlled pressure.8. The method of claim 7 and further comprising: determining whether thepressure in the anode loop exceeds a threshold pressure; and modifying aspeed of the anode loop blower to modify the pressure in the anode loopin response to the determination.
 9. The method of claim 8 and furthercomprising: determining whether the pressure in the anode loop fallsbelow a lower threshold pressure; and modifying the speed of the anodeloop blower to increase the speed of the anode loop blower in responseto the pressure in the anode loop exceeding the lower thresholdpressure.
 10. The method of claim 7 and further comprising: determiningwhether the pressure in the anode loop exceeds an upper thresholdpressure; and modifying the speed of the anode loop blower to decreasethe speed of the anode loop blower in response to the pressure in theanode loop exceeding the upper threshold pressure.
 11. The method ofclaim 7 and further comprising controlling a first cooling mechanism tomaintain a temperature within the fuel cell within a predeterminedtemperature range.
 12. The method of claim 7 and further comprisingcontrolling a second cooling mechanism to maintain a temperature withinthe hydrogen generator within a predetermined temperature range.
 13. Thecontroller of claim 7 wherein the anode loop recirculates hydrogengenerated by the hydrogen generator back to the hydrogen generator. 14.The controller of claim 7 wherein the anode loop provides hydrogen tothe anode of the fuel cell via a secondary path of the anode loop.
 15. Anon-transitory machine-readable storage device having instructions forexecution by a processor of a machine to cause the processor to performoperations to perform a method, the operations comprising: receiving apressure value of sensed pressure in an anode loop of the fuel cellbased power generator, wherein the anode loop includes a hydrogengenerator that receives hydrogen containing water from the anode loopand an anode loop blower; and controlling an anode loop blower speedsuch that the hydrogen generator generates hydrogen in response toreceiving the hydrogen containing water and provides the hydrogen to ananode of a fuel cell via the anode loop blower and the anode loop at acontrolled pressure.
 16. The device of claim 15 wherein the operationsfurther comprise: determining whether the pressure in the anode loopexceeds a threshold pressure; and modifying a speed of the anode loopblower to modify the pressure in the anode loop in response to thedetermination.
 17. The device of claim 15 wherein the operations furthercomprise: determining whether the pressure in the anode loop falls belowa lower threshold pressure; and modifying the speed of the anode loopblower to increase the speed of the anode loop blower in response to thepressure in the anode loop exceeding the lower threshold pressure. 18.The device of claim 15 wherein the operations further comprise:determining whether the pressure in the anode loop exceeds an upperthreshold pressure; and modifying the speed of the anode loop blower todecrease the speed of the anode loop blower in response to the pressurein the anode loop exceeding the upper threshold pressure.